Synthesis, carbonic anhydrase inhibition studies and modelling investigations of phthalimide-hydantoin hybrids.

A novel series of hydantoins incorporating phthalimides has been synthesised by condensation of activated phthalimides with 1-aminohydantoin and investigated for their inhibitory activity against a panel of human (h) carbonic anhydrase (CA, EC 4.2.1.1): the cytosolic isoforms hCA I, hCA II, and hCA VII, secreted isoform hCA VI, and the transmembrane hCA IX, by a stopped-flow CO2 hydrase assay. Although all newly developed compounds were totally inactive on hCA I and mainly ineffective towards hCA II, they generally exhibited moderate repressing effects on hCA VI, VII, and IX with KIs values in the submicromolar to micromolar ranges. The salts 3a and 3b, followed by derivative 5, displayed the best inhibitory activity of all the evaluated compounds and their binding mode was proposed in silico. These compounds can also be considered interesting starting points for the development of novel pharmacophores for this class of enzyme inhibitors.

Sulfonamide-incorporated bis(α-aminophosphonates) as promising carbonic anhydrase inhibitors: Design, synthesis, biological evaluation, and X-ray crystallographic studies.

A novel series of sulfonamide-incorporated bis(α-aminophosphonates) acting as effective carbonic anhydrase (CA, EC 4.2.1.1) inhibitors is reported. The synthesized bivalent ligands were tested against five human (h) isoforms, hCA I, hCA II, hCA VII, hCA IX, and hCA XIII. Such derivatives showed high activity and selectivity against the cancer-related, membrane-bound isoform hCA IX, and among them, compound 5h, tetraisopropyl (1,3-phenylenebis{[(4-sulfamoylphenyl)amino]methylene})bis(phosphonate) showed a KI of 15.1 nM, being highly selective against this isoform over all other investigated ones (hCA I/IX = 42; hCA II/IX = 6, hCA VII/IX = 3, hCA XIII/IX = 5). Therefore, compound 5h could be a potential lead for the development of selective anticancer agents. The newly developed sulfonamides were also found effective inhibitors against the cytosolic hCA XIII isoform. Compound 5i displayed the best inhibition against this isoform with a KI of 17.2 nM, equal to that of the well-known inhibitor acetazolamide (AAZ), but significantly more selective over all other tested isoforms (hCA I/XIII = 239; hCA II/XIII = 23, hCA VII/XIII = 2, hCA IX/XIII = 3) compared to AAZ.

4-Cyanamido-substituted benzenesulfonamides act as dual carbonic anhydrase and cathepsin inhibitors.

A set of novel N-cyano-N-substituted 4-aminobenzenesulfonamide derivatives were synthesized and investigated for their inhibitory activity against four cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isoforms (hCA I, II, VII and XIII) and two cathepsins (S and B). N-alkyl/benzyl-substituted derivatives were revealed to be very potent inhibitors against brain-associated hCA VII, but inactive against both cathepsins. On the other hand, N-acyl-substituted derivatives displayed significant inhibitory activities against cathepsin S, but only moderate to poor inhibitory potency against hCA VII. Both hCA VII and cathepsin S have recently been validated as therapeutic targets in neuropathic pain. This study provided an excellent starting point for further structural optimization of this class of bifunctional compounds to enhance their inhibitory activity and selectivity against hCA VII and cathepsin S and to achieve new compounds with an attractive dual mechanism of action as anti-neuropathic agents.

2-((1H-Benzo[d]imidazol-2-yl)amino)benzo[d]thiazole-6-sulphonamides: a class of carbonic anhydrase II and VII-selective inhibitors.

A small library of substituted cyclic guanidine incorporated benzothiazole-6-sulphonamides was synthesized. All obtained compounds were investigated for their inhibitory activity against the key brain-associated human carbonic anhydrase isoform hCA VII (a promising target for the treatment of neuropathic pain) and three isoforms expressed in brain and other tissues, hCA I, II, and IV. Sulphaguanidine derivatives 9a-d were inactive on the all investigated isoforms while the primary sulphonamide containing guanidines 6a-c and 7a-c were inactive towards hCA IV but displayed inhibiting properties on hCA I, II, and VII with KIs values in the low nanomolar to micromolar ranges. The results indicated that isoforms hCA II and VII were potently and selectively inhibited by these compounds, whereas the cytosolic hCA I was less sensitive to inhibition. The derivatives reported in this study might be useful for design of more potent and selective inhibitors of hCA II and VII.

Investigation of novel alkyl/benzyl (4-sulphamoylphenyl)carbamimidothioates as carbonic anhydrase inhibitors.

A library of novel alkyl/benzyl (4-sulphamoylphenyl)carbamimidothioates was synthesised by selective S-alkylation of the easily accessible 4-thioureidobenzenesulphonamide. The compounds were assayed as inhibitors of four human (h) carbonic anhydrase isoforms hCA I, II, VII, and XIII, as well as three bacterial enzymes belonging to the ß-CA class, MscCA from Mammaliicoccus (Staphylococcus) sciuri and StCA1 and StCA2, from Salmonella enterica (serovar Typhimurium). Most compounds investigated here exhibited moderate to low nanomolar inhibition constants against hCA I, II, and VII. The cytosolic hCA XIII was also inhibited by these compounds, but not as effective as hCA I, II, and VII. Several compounds were very effective against MscCA and StCA1. StCA2 was less inhibited compared to MscCA and StCA1. Some compounds showed considerable selectivity for inhibiting some CA isoforms. They may thus be considered as interesting starting points for the discovery and development of novel therapeutic agents belonging to this class of enzyme inhibitors.

Novel thiazolone-benzenesulphonamide inhibitors of human and bacterial carbonic anhydrases.

A small library of novel thiazolone-benzenesulphonamides has been prepared and evaluated for their ability to inhibit three human cytosolic carbonic anhydrases (hCA I, hCA II, and hCA VII) and three bacterial carbonic anhydrases (MscCAß, StCA1, and StCA2). All investigated hCAs were inhibited by the prepared compounds 4a-4j in the low nanomolar range. These compounds were effective hCA I inhibitors (KIs of 31.5-637.3 nM) and excellent hCA II (KIs in the range of 1.3-13.7 nM) and hCA VII inhibitors (KIs in the range of 0.9-14.6 nM). The most active analog in the series, 4-((4-oxo-5-propyl-4,5-dihydrothiazol-2-yl)amino)benzenesulphonamide 4d, strongly inhibited bacterial MscCAß, with KI of 73.6 nM, considerably better than AAZ (KI of 625 nM). The tested compounds displayed medium inhibitory potency against StCA1 (KIs of 69.2-163.3 nM) when compared to the standard drug (KI of 59 nM). However, StCA2 was poorly inhibited by the sulphonamides reported here, with KIs in the micromolar range between 275.2 and 4875.0 nM.

Derivatives of 4-methyl-1,2,3-benzoxathiazine 2,2-dioxide as selective inhibitors of human carbonic anhydrases IX and XII over the cytosolic isoforms I and II.

A series of 4-methyl-1,2,3-benzoxathiazine-2,2-dioxides with various substituents in 5, 6 or 7 positions was obtained from corresponding 2'-hydroxyacetophenones in their reaction with sulphamoyl chloride. 6- and 7-aryl substituted 4-methyl-1,2,3-benzoxathiazine-2,2-dioxides were obtained from aryl substituted 2'-hydroxyacetophenonesprepared from 4- or 5-bromo-2'-hydroxyacetophenones via two-step protocol. 4-Methyl-1,2,3-benzoxathiazine-2,2-dioxides were investigated as inhibitors of four human (h) carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, off-target cytosolic hCA I and II, and target transmembrane, tumour-associated hCA IX and XII. Twenty derivatives of 4-methyl-1,2,3-benzoxathiazine 2,2-dioxide were obtained. With one exception (compound2a), they mostly act as nanomolar inhibitors of target hCA IX and XII. Basically, all screened compounds express none or low inhibitory properties towards off-target hCA I. hCA II is inhibited in micromolar range. Overwhelming majority of 4-methyl-1,2,3-benzoxathiazine 2,2-dioxides express excellent selectivity towards CA IX/XII over hCA I as well as very good selectivity towards CA IX/XII over hCA II.

4-Cyanamidobenzenesulfonamide derivatives: a novel class of human and bacterial carbonic anhydrase inhibitors.

A one-pot two-step protocol was developed for the synthesis of a series of novel 4-cyanamidobenzenesulfonamides from easily accessible methyl (4-sulfamoylphenyl)-carbamimidothioate. The new sulphonamides were investigated as inhibitors of the enzyme carbonic anhydrase (CA, EC 4.2.1.1), the human (h) cytosolic isoforms hCA I, II, VII, and XIII, as well as three bacterial enzymes belonging to the ß-CA class, MscCA from Mammaliicoccus (Staphylococcus) sciuri and StCA1 and StCA2, from Salmonella enterica (serovar Typhimurium). The human isoforms were generally effectively inhibited by these compounds, with a clear structure-activity relationship privileging long aliphatic chains (C6, C7 and C18) as substituents at the cyanamide functionality. The bacterial CAs were also inhibited by these compounds, but not as effective as the hCAs. The most sensitive enzyme to these inhibitors was StCA1 (KIs of 50.7 - 91.1 nM) whereas SscCA was inhibited in the micromolar range (KIs of 0.86-9.59 µM).

1,2,3-Benzoxathiazine-2,2-dioxides - effective inhibitors of human carbonic anhydrases.

A series of 1,2,3-benzoxathiazine-2,2-dioxides possessing various substituents in the 5, 7, or 8 position was obtained from corresponding 2-hydroxybenzaldehydes in their reaction with sulfamoyl chloride. 5-, 7-, and 8-aryl substituted 1,2,3-benzoxathiazine-2,2-dioxides were prepared from aryl substituted 2-hydroxybenzaldehydes obtained from 3-, 4-, or 6-bromo-2-hydroxybenzaldehydes via two-step protocol. 1,2,3-Benzoxathiazine-2,2-dioxides were investigated for the inhibition of four human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, cytosolic hCA I and II and tumour-associated transmembrane hCA IX and XII. Twenty four derivatives of 1,2,3-benzoxathiazine 2,2-dioxide were obtained. Most of them act as nanomolar inhibitors of hCA IX and XII. Almost all compounds except 2d and 5a-e also express nanomolar inhibitory activity for hCA II. hCA I is poorly inhibited or not inhibited by 1,2,3-benzoxathiazine 2,2-dioxides. Some of the new derivatives exhibit promising selectivity towards CA IX/XII over hCA I, although none of the compounds are selective towards CA IX/XII over both hCA I and II.

3H-1,2-Benzoxaphosphepine 2-oxides as selective inhibitors of carbonic anhydrase IX and XII.

The synthesis of 3H-1,2-benzoxaphosphepine 2-oxides and evaluation of their inhibitory activity against human carbonic anhydrase (hCA) isoforms I, II, IX, and XII are described. The target compounds were obtained via a concise synthesis from commercial salicylaldehydes and displayed low to sub-micromolar inhibition levels against the tumour-associated isoforms hCA IX and XII. All obtained benzoxaphosphepine 2-oxides possess remarkable selectivity for inhibition of hCA IX/XII over the off-target cytosolic hCA isoforms I and II, whose inhibition may lead to side effects.

Aryl derivatives of 3H-1,2-benzoxaphosphepine 2-oxides as inhibitors of cancer-related carbonic anhydrase isoforms IX and XII.

A range of 3H-1,2-benzoxaphosphepine 2-oxide aryl derivatives with various substitution patterns at positions 7, 8, or 9 of the scaffold was synthesised in five steps from the commercially available salicylaldehydes. All of the newly obtained compounds were studied for their inhibition potency against carbonic anhydrase (CA) isoforms I, II, IX, and XII. Delightfully, these compounds showed a striking selectivity for the cancer-associated CA IX and XII over the cytosolic CA I and II, whose inhibition may lead to side-effects. Overall, a structure-activity relationship (SAR) revealed that 7- and 8-substituted aryl derivatives were more effective inhibitors of CA IX and XII than 9-substituted derivatives. In addition, the fluorine-containing analogues emerged as the most potent CA IX/XII inhibitors in this series.

Selected strategies to fight pathogenic bacteria.

Natural products and analogues are a source of antibacterial drug discovery. Considering drug resistance levels emerging for antibiotics, identification of bacterial metalloenzymes and the synthesis of selective inhibitors are interesting for antibacterial agent development. Peptide nucleic acids are attractive antisense and antigene agents representing a novel strategy to target pathogens due to their unique mechanism of action. Antisense inhibition and development of antisense peptide nucleic acids is a new approach to antibacterial agents. Due to the increased resistance of biofilms to antibiotics, alternative therapeutic options are necessary. To develop antimicrobial strategies, optimised in vitro and in vivo models are needed. In vivo models to study biofilm-related respiratory infections, device-related infections: ventilator-associated pneumonia, tissue-related infections: chronic infection models based on alginate or agar beads, methods to battle biofilm-related infections are discussed. Drug delivery in case of antibacterials often is a serious issue therefore this review includes overview of drug delivery nanosystems.

May 1,2-Dithiolane-4-carboxylic Acid and Its Derivatives Serve as a Specific Thioredoxin Reductase 1 Inhibitor?

Thioredoxin reductase is an essential enzyme that plays a crucial role in maintaining cellular redox homeostasis by catalyzing the reduction of thioredoxin, which is involved in several vital cellular processes. The overexpression of TrxR is often associated with cancer development. A series of 1,2-dithiolane-4-carboxylic acid analogs were obtained to verify the selectivity of 1,2-dithiolane moiety toward TrxR. Asparagusic acid analogs and their bioisoters remain inactive toward TrxR, which proves the inability of the 1,2-dithiolane moiety to serve as a pharmacophore during the interaction with TrxR. It was found that the Michael acceptor functionality-containing analogs exhibit higher inhibitory effects against TrxR compared to other compounds of the series. The most potent representatives exhibited micromolar TrxR1 inhibition activity (IC50 varied from 5.3 to 186.0 µM) and were further examined with in vitro cell-based assays to assess the cytotoxic effects on various cancer cell lines and cell death mechanisms.

Inhibition Studies on Human and Mycobacterial Carbonic Anhydrases with N-((4-Sulfamoylphenyl)carbamothioyl) Amides.

A library of structurally diverse N-((4-sulfamoylphenyl)carbamothioyl) amides was synthesized by selective acylation of easily accessible 4-thioureidobenzenesulfonamide with various aliphatic, benzylic, vinylic and aromatic acyl chlorides under mild conditions. Inhibition of three α-class cytosolic human (h) carbonic anhydrases (CAs) (EC 4.2.1.1); that is, hCA I, hCA II and hCA VII and three bacterial ß-CAs from Mycobacterium tuberculosis (MtCA1-MtCA3) with these sulfonamides was thereafter investigated in vitro and in silico. Many of the evaluated compounds displayed better inhibition against hCA I (KI = 13.3-87.6 nM), hCA II (KI = 5.3-384.3 nM), and hCA VII (KI = 1.1-13.5 nM) compared with acetazolamide (AAZ) as the control drug (KI values of 250, 12.5 and 2.5 nM, respectively, against hCA I, hCA II and hCA VII). The mycobacterial enzymes MtCA1 and MtCA2 were also effectively inhibited by these compounds. MtCA3 was, on the other hand, poorly inhibited by the sulfonamides reported here. The most sensitive mycobacterial enzyme to these inhibitors was MtCA2 in which 10 of the 12 evaluated compounds showed KIs (KI, the inhibitor constant) in the low nanomolar range.

4-(3-Alkyl/benzyl-guanidino)benzenesulfonamides as selective carbonic anhydrase VII inhibitors.

The treatment of chronic neuropathic pain remains one of the most challenging of all neurological diseases and very much an art. There exists no consensus for the optimal management of this condition at the moment. Gaining inspiration from recent studies which pointed out the involvement of brain-associated carbonic anhydrase (CA, EC 4.2.1.1) isoform VII in the pathology of various neurodegenerative diseases, which highlighted the relationship between selective inhibition of this isozyme and relieve of neuropathic pain, herein we report the synthesis and CA VII inhibitory activity of novel 4-(3-alkyl/benzyl-guanidino)benzenesulfonamides. Ten benzyl-substituted and five alkyl-substituted 4-guanidinobenzenesulfonamide derivatives were obtained, some of which (7c, 7h, 7m and 7o) exhibited satisfactory selectivity towards CA VII over CA I and II, with KI-s in the subnanomolar range and good selectivity indexes for inhibiting the target versus the off-target isoforms.

Benzenesulfonamides Incorporating Hydantoin Moieties Effectively Inhibit Eukaryoticand Human Carbonic Anhydrases.

A series of novel 1-(4-benzenesulfonamide)-3-alkyl/benzyl-hydantoin derivatives were synthesized and evaluated for the inhibition of eukaryotic and human carbonic anhydrases (CAs, EC 4.2.1.1). The prepared compounds were screened for their hCA inhibitory activities against three cytosolic isoforms as well as two ß-CAs from fungal pathogens. The best inhibition was observed against hCA II and VII as well as Candida glabrata enzyme CgNce103. hCA I and Malassezia globosa MgCA enzymes were, on the other hand, less effectively inhibited by these compounds. The inhibitory potency of these compounds against CAs was found to be dependent on the electronic and steric effects of substituent groups on the N3-position of the hydantoin ring, which included alkyl, alkenyl and substituted benzyl moieties. The interesting results against CgNce103 make the compounds of interest for investigations in vivo as potential antifungals.

Reconsidering anion inhibitors in the general context of drug design studies of modulators of activity of the classical enzyme carbonic anhydrase.

Inorganic anions inhibit the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) generally by coordinating to the active site metal ion. Cyanate was reported as a non-coordinating CA inhibitor but those erroneous results were subsequently corrected by another group. We review the anion CA inhibitors (CAIs) in the more general context of drug design studies and the discovery of a large number of inhibitor classes and inhibition mechanisms, including zinc binders (sulphonamides and isosteres, dithiocabamates and isosteres, thiols, selenols, benzoxaboroles, ninhydrins, etc.); inhibitors anchoring to the zinc-coordinated water molecule (phenols, polyamines, sulfocoumarins, thioxocoumarins, catechols); CAIs occluding the entrance to the active site (coumarins and derivatives, lacosamide), as well as compounds that bind outside the active site. All these new chemotypes integrated with a general procedure for obtaining isoform-selective compounds (the tail approach) has resulted, through the guidance of rigorous X-ray crystallography experiments, in the development of highly selective CAIs for all human CA isoforms with many pharmacological applications.

Benzoxepinones: A new isoform-selective class of tumor associated carbonic anhydrase inhibitors.

Benzoxepinones ("homocoumarins") are identified as a new class of selective inhibitors for tumor associated human carbonic anhydrases (hCA, EC 4.2.1.1) isoforms IX and XII. Similar to coumarins, they do not inhibit or poorly inhibit cytosolic human (h) isoforms hCA I and II, but act as nanomolar inhibitors of the trans-membrane, tumor associated isoforms hCA IX and XII.

The antibiotic furagin and its derivatives are isoform-selective human carbonic anhydrase inhibitors.

The clinically used antibiotic Furagin and its derivatives possess inhibitory activity on human (h) carbonic anhydrases (CA, EC 4.2.1.1), some of which are highly expressed in various tissues and malignancies (hCA IX/XII). Furagin exhibited good hCA IX and XII inhibition with KIs of 260 and 57 nM, respectively. It does not inhibit off-target CA I and poorly inhibited CA II (KI = 9.6 µM). Some synthesised Furagin derivatives with aminohydantoin moieties as zinc binding group exhibited weak inhibition of CA I/II, and good inhibition of CA IX/XII with KIs ranging from 350 to 7400 and 150 to 5600 nM, respectively. Docking and molecular dynamics simulations suggest that selectivity for the cancer-associated CA IX/XII over CA II is due to strong H-bond interactions in CA IX/XII, involving the tail orientated towards hydrophobic area of the active site. These results suggest a possible drug repurposing of Furagin as anti-cancer agent.

Sulfocoumarins as dual inhibitors of human carbonic anhydrase isoforms IX/XII and of human thioredoxin reductase.

The hypothesis that sulfocoumarin acting as inhibitors of human carbonic anhydrase (CA, EC 4.2.1.1) cancer-associated isoforms hCA IX and - hCA XII is being able to also inhibit thioredoxin reductase was verified and confirmed. The dual targeting of two cancer cell defence mechanisms, i.e. hypoxia and oxidative stress, may both contribute to the observed antiproliferative profile of these compounds against many cancer cell lines. This unprecedented dual anticancer mechanism may lead to a new approach for designing innovative therapeutic agents.